Focus On: Glass
  Gary Sanders
  TMT Project Manager

TMT needs a lot of glass. Our primary mirror consists of 738 hexagons of glass, 1.2 meters across at the widest point (about 48" for those who are more comfortable with English units) and 40 mm thick (that is close to 1 9/16" thick). The total area is about 700 square meters (about 1.5 basketball courts). This is a lot of glass.

It is not ordinary glass. This glass is "zero-expansion glass". This means that as the temperature changes, the glass pieces do not change dimensions. This is very important for TMT as our mirrors must be polished into very precise shapes and the gaps between the hexagonal segments must be very small so as to properly collect all of the light even if the telescope is pointed away from zenith (straight up) where gravity will make everything sag a tiny bit.

There are only a few firms in the world who make such special glass. They know that TMT may be a pretty good customer in a few years. We want those companies to know what we will need and about when we will need it and we ask them questions about detailed specifications (to make sure we do not request glass that is too expensive) and we keep in touch. Our partner polishing firms are studying how to cheaply polish our mirrors and they, too, keep in touch with the glass suppliers.

Someday, I hope soon, formal documents will go out to suppliers requesting firm bids to supply glass and to polish the mirror segments and to test them against our required shapes. This will be where open fair competition will take place. This is a tense and exciting process. The outcome is winning firms, hopefully very low bids, successful jobs completed with beautiful mirrors in TMT, and a bit of profit for the valiant firms who take on this demanding work.

In the meantime, we all keep each other informed and ask questions to help our planning. Some of this happens at major conferences and meetings. As I write this, the SPIE Astronomical Telescopes and Instrumentation meeting, a gargantuan affair held every two years, is winding down in Orlando, Florida. Such meetings always have asset of accompanying industrial exhibits. In the course of this meeting, I wandered around the exhibits, turned a corner and spied (not a pun) a piece of glass that was very attractive to me. Lo and behold, it was a TMT glass segment blank. Right in front of me, it was a pleasant surprise.

Randy VanBrocklin, Sales Engineer for Specialty Materials (that does sound like our product line) at Corning, explained that, yes, the company had cast this blank on its own initiative. The idea was to catch our attention and send a clear message that they are interested in supplying TMT's needs.

It worked. Randy and Corning get an A in marketing. They caught our attention. Larry Stepp (TMT Telescope Department Head) and I gathered with Randy to be photographed next to what might someday be a real TMT segment (see photo).

Thank you, Randy and Corning, for your interest. We appreciate your overture. But alas, you will still have to bid when our Request for Proposals is sent out. Good luck!